SANAA, Sept. 18 (Xinhua) -- UN envoy to Yemen Martin Griffiths left Yemen's capital Sanaa on Tuesday after holding two-day intensified talks to revive peace process with dominant Houthi rebels.

Griffiths did not hold press conference at the airport, nor did his security convoy allow journalists to take pictures.

On Sunday, Griffiths arrived in Sanaa and met senior Houthi officials, including the group leader Abdulmalik al-Houthi.

Houthi spokesman Mohammed Abdulsalam said on his Twitter account that "leader Abdulmalik al-Houthi met Griffiths in Sanaa."

"They agreed on a set of preparations for paving the way to hold a future peace talk to end the war," Abdulsalam said without elaborating further details.

Griffiths' office has not made a statement on the results of his visit.

Last Tuesday, Griffiths told a Security Council meeting on the situation in Yemen, where the war has been escalating across all fronts. "The level of confidence is at its lowest and the human and humanitarian cost is ever rising," he told the council.

Following the collapse of peace talks in Geneva on Sept. 8, the government forces backed by the Saudi-led coalition warplanes advanced into the edges of rebel-held Red Sea port city of Hodeidah.

The forces tightened siege on the city and main roads linking the port with Sanaa, causing a sharp economic crisis on the rebel-controlled northern cities.

Hodeidah port is the entry point of about 70 percent of the country's food, medicines, aid and fuel.

The Geneva talks failed after the Houthi rebels refused to attend, claiming that the UN did not guarantee the safe return of the Houthi delegation.

Two previous attempts in Switzerland and Kuwait in 2016 brokered by the United Nations also collapsed.

Yemen's war has so far killed 10,000 people, mostly civilians, and displaced 3 million others.

Saudi Arabia is leading an Arab military coalition that intervened in Yemen in 2015 to support the government of President Abd-Rabbu Mansour Hadi after the Houthi rebels forced him into exile.